1. Field
Embodiments of the present invention relate to a fusing unit including a paper-contact heating region through which a recording medium passes and a paper non-contact heating region, through which the recording medium does not pass, having different heating values per unit area, and an image forming apparatus using the same.
2. Description of the Related Art
An electrophotographic image forming apparatus prints an image on a recording medium by irradiating light to a charged photosensitive material to form an electrostatic latent image, developing the electrostatic latent image using a toner, and transferring and fusing (fixing) the same on the recording medium. The electrophotographic image forming apparatus includes a fusing unit on a printing passage so as to fuse the transferred toner.
The fusing unit heats and pressurizes the toner-transferred recording medium so as to fuse (fix) the transferred toner on the recording medium, instead of separating the transferred toner from the recording medium. The fusing unit includes a heating roller to heat the transferred recording medium and a pressurizing member to apply pressure to the toner-transferred recording medium.
The heating roller and the pressurizing member may have a greater width than that of the recording medium, since the recording medium may not always be supplied to the fusing unit while being accurately arranged at an intended position.
The heating roller includes a paper-contact heating region through which the recording medium passes, and a paper non-contact heating region through which the recording medium does not pass. Heat generated to heat the recording medium is transferred to the paper-contact heating region of the heating roller, while generated heat is accumulated in the heating roller in the paper non-contact heating region of the heating roller, instead of being transferred to the recording medium.
As a result, a temperature of the paper non-contact heating region, in which heat is accumulated, gradually increases. When accumulated heat is not dissipated, the heating roller may overheat and cause a fire.
In an attempt to address these problems, in conventional methods, heat accumulated in the paper non-contact heating region may be emitted by idling the heating roller, while the heating roller of the fusing unit does not generate heat.
However, this cyclic idling of the heating roller requires a consumption of power to idle the heating roller and causes an increase in printing time.